Warpage of organic substrates is an important challenge in electronic packaging area because it affects device assembling process and device reliability. The causes for the initial warpage include asymmetric mechanical properties such as coefficients of thermal expansion and modulus of constituent materials. The asymmetry in chemical expansion property also causes substrate warpage.
If the substrate's warpage value does not meet the standards, the substrate is rejected lowering the yield. That is, the organic substrate with big warpage is thrown away without being used.
Therefore it is necessary to correct the substrate's warpage automatically after the production so that its value becomes within the standards and improve the yields.